Although obviously changed a lot from the 4th century AD, when it was the largest centrally planned building in the Western world, the church of St Lawrence has remained fairly faithful to its original Early Christian plan. The reconstruction of the basilica between 1573 and 1619 - to a brilliant project by Martino Bassi - didn't affect it.
Inside, chapels of various age and structure make a sunburst pattern. The chapel of Sant'Aquilino (to the right of the entrance) is a former 4th century mausoleum, with remains of the original mosaic decorations.

It was in Piazza Vetra, the back of San Lorenzo, that capital punishments used to take place.